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Haemolytic Anaemia Flashcards

1
Q

what is haemolytic anaemia?

A

anaemia caused by the destruction or ‘lysis’ of red blood cells

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2
Q

what are the different types of haemolytic anaemia?

A
  • hereditary or acquired
  • intravascular or extravascular
  • autoimmune (Coombs +ve) or non-autoimmune (Cooms -ve)
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3
Q

what are the biochemical features of haemolytic anaemia?

A
  • low Hb
  • high bilirubin (unconjugated)
  • reticulocytosis
  • raised LDH
  • raised urinary urobilinogen
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4
Q

what is the pathophysiology of intravascular haemolytic anaemia?

A
  1. occurs in the blood stream
  2. release of cellular contents (particularly Hb) into the circulation
  3. excess of Hb combines with haptoglobin and albumin, is lost in the urine and stored in tubular epithelial cells
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5
Q

what are the causes of intravascular haemolytic anaemia?

A
  • intrinsic cellular injury (e.g. G6DP)
  • intravascular complement mediated lysis (e.g. autoimmune haemolytic anaemia)
  • paroxysmal nocturnal haemoglobinuria and acute transfusion reactions
  • mechanical injury (microangiopathic haemolytic anaemia and cardiac valves)
  • autoimmune haemolytic anaemia
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6
Q

what is glucose-6-phosphate deficiency (G6PD) features?

A
  • x-linked recessive red-cell enzyme disorder
  • present in neonatal period with jaundice
  • present later in life with episodic intravascular haemolysis following exposure to oxidative stressors
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7
Q

what are the triggers of G6DP?

A
  • intercurrent illness or infection
  • fava beans
  • henna
  • medications
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8
Q

what drugs can precipitate G6PD deficiency?

A
  • anti-malarials - primaquine
  • ciprofloxacin
  • sulfa-drugs
  • nitrofurantoin
  • dapsone
  • NSAIDs/aspirin
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9
Q

what investigations should be undertaken in G6PD?

A
  • blood film = heniz bodies and bite cells
  • diagnostic test = enzyme assay
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10
Q

what is the management of G6PD?

A
  • avoidance of precipitants
  • rarely require transfusions
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11
Q

what is the pathophysiology of extravascular haemolytic anaemia?

A
  1. occurs in the reticuloendothelial system (the spleen and liver)
  2. not associated with dramatic release of free haemoglobin into the circulation
  3. splenomegaly and hepatomegaly
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12
Q

what are the causes of extravascular haemolytic anaemia?

A
  • abnormal red blood cells (sickle cell anaemia and hereditary spherocytosis)
  • normal cells marked by antibodies for splenic phagocytosis
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13
Q

what is the inheritance of hereditary spherocytosis?

A
  • autosomal dominant condition (northern european)
  • caused by mutations in structural red cell membrane proteins
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14
Q

what is the pathophysiology of hereditary spherocytosis?

A

defect in erythrocyte cell membrane
1. abnormal sections of red celll membrane are removed by the spleen
2. reduced surface area to volume ratio
3. spherical distortion of cells
4. cells haemolyse (extravasculae haemolysis)
5. removed from circulation in the spleen

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15
Q

what investigations should be undertaken in hereditary spherocytosis?

A
  • blood film = spherocytes
  • positive family history
  • EMA binding test
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16
Q

what are the clinical features of hereditary spherocytosis?

A
  • neonatal or childhood onset jaundice/anaemia
  • splenomegaly
17
Q

what is the management of hereditary spherocytosis?

A
  • folic acid supplementation
  • severe = splenectomy before the age of 5 years
18
Q

what key investgations need to be undertaken in autoimmune haemolytic anaemia (AIHA)?

A

direct Coombs test
patients with AIHA have antibodies directed against cell surface markers on the red blood cell. the Coombs test uses antibodies against these autoantibodies to cross link and agglutinate the red cells

19
Q

what are the two different types of coombs +ve AIHA?

A
  • warm
  • cold
20
Q

what is the pathophysiology of warm autoimmune haemolytic anaemia (AIHA)?

A
  1. IgG mediated extravascular haemolytic disease
  2. spleen tags cells for splenic phagocytosis
21
Q

what are the causes of warm AIHA?

A
  • idiopathic
  • lymphoproliferative neoplasms (CLL and lymphoma)
  • drugs - e.g. methnyldopa
  • SLE
22
Q

what is the managment of warm AIHA?

A
  1. steroids - prednisolone
  2. immunosuppressives and splenectomy

if severe anaemia = blood transfusions

23
Q

what is the pathophysiology of cold AIHA?

A
  1. IgM mediated haemolytic disease
  2. IgM fixes complement causing direct intravascular haemolysis (known as cold agglutinins)
24
Q

what are the causes of cold AIHA?

A
  • idiopathic
  • post-infectious haemolytic anaemias - occuring 2-3 weeks after infection
25
Q

name some examples of coombs -ve haemolytic anaemia

A
  • microangiopathic haemolytic anaemia
  • paroxysmal nocturnal haemoglobinuria
  • physical lysis of red cells (e.g. malaria)
  • haemolytic uraemic syndrome - E.Coli
  • infectious causes DIC - e,g, fulminant mengiococcaemia
26
Q

what is the pathophysiology of microangiopathic haemolytic anaemia?

A

intravascular haemolytic disease
1. physical lysis of red cells by deposited fibrin strands
2. presence of schistocytes (fragments of red blood cells) on blood film

27
Q

what are the features of microangiopathic haemolytic anaemia?

A
  • isolated
  • or occur in associated with thrombotic microangiopathy syndrome (e.g haemolyic uraemic syndrome and thrombotic thrombocytopenia purpura)
  • severe cases = associated with disseminated intravascular coagulation
28
Q

what is paroxysmal nocturnal haemoglobinuria?

A

rare aquired stem cell disorder of unknown aetiology

29
Q

what is the pathophysiology of paroxysmal noctural haemoglobinuria?

A
  1. abnormal surface glycoprotein expressed on a subclone of red blood cells
  2. marks these cells for complement mediated haemolysis
  3. severity depends on size of this subclone
30
Q

what are the clinical features of paroxysmal nocturnal haemoglobinuria?

A
  • present in early adulthood with nocturnal episodes of intravascular haemolysis
  • associated with other stem cell defects
  • increased risk of thrombosis

it is not known why this occurs at night

31
Q

how is paroxysmal nocturnal haemoglobinuria diagnosed?

A

flow cytometry

32
Q

in what conditions does physical lysis of red cells occur?

A
  • falciparum malaria
  • babesiosis (diseases in which the parasite grows in the red cell cytoplasm)
  • prosthetic heart valves
33
Q

what type of anaemia is haemolytic anaemia?

A

normocytic anaemia with riased reticulocyte count

34
Q

what is the treatment of choice for acute and severe falciparum malaria?

A

IV artesunate

haematology (14 decks)

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